Fluted osteotome and surgical method for use

ABSTRACT

A surgical method and tool for expanding an initial osteotomy ( 42 ) to receive a dental implant ( 44 ). An osteotome ( 22 ) having a tapered working end ( 28 ) is inserted into the initial osteotomy ( 42 ). The initial osteotomy ( 42 ) is enlarged by simultaneously rotating and pushing the working end ( 28 ) of the tapered osteotome ( 22 ) into the osteotomy ( 42 ). One or more burnishing edges ( 40 ) concentrate the pushing and rotational force in outward normal and tangential component forces against the interior surface of the osteotomy ( 42 ) to incrementally expand the osteotomy ( 42 ) with little to no removal of bone material ( 46 ). The inserting and enlarging steps are repeated, as needed, with progressively larger tapered osteotomes ( 22 ) until an osteotomy ( 42 ) of predetermined size is achieved. Finally, a fixture portion of a dental implant ( 44 ) is installed into the expanded osteotomy ( 42 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. Ser. No. 13/427,391 filedMar. 22, 2012, which claims priority to Provisional Patent ApplicationNo. 61/466,579 filed Mar. 23, 2011, the entire disclosures of which arehereby incorporated by reference and relied upon.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates generally to osteotomes, and more particularly tosurgical methods for expanding an initial osteotomy to receive a dentalimplant.

Related Art

In its most basic form the placement of a dental implant requires apreparation into the bone using either hand osteotomes or precisiondrills with highly regulated speed to prevent burning or pressurenecrosis of the bone. After a variable amount of time to allow the boneto grow on to the surface of the fixture portion of an implant, arestoration can be placed on the fixture. See for example FIG. 1.

According to current techniques, at edentulous (without teeth) jaw sitesthat need expansion, a pilot hole is bored into the recipient bone,taking care to avoid the vital structures. The pilot hole is thenexpanded using progressively wider expander devices (i.e., osteotomes),manually advanced by the surgeon (typically between three and sevensuccessive expanding steps, depending on implant width and length). Seefor example FIG. 2. Once the receiving hole has been properly prepared,a fixture screw (usually self-tapping) is screwed into place at aprecise torque so as not to overload the surrounding bone.

The osteotome technique has become widely utilized in situationsrequiring ridge expansion. By nature, the osteotome technique is atraumatic procedure. The instruments are advanced with the impact of asurgical mallet, which compacts and expands the bone in the process ofpreparing osteotomy sites that will allow implant placement. (FIG. 2.)Treatment of mandibular sites is often limited due to the increaseddensity and reduced plasticity exhibited by the bone. Additionally,since the osteotome is inserted by hammering, the explosive nature ofthe percussive force provides limited control over the expansionprocess, which often leads to unintentional displacement or fracture ofthe labial plate of bone. Many patients do not tolerate the osteotometechnique well, frequently complaining about the impact from thesurgical mallet. In addition, reports have documented the development ofa variety of complications that result from the percussive trauma,including vertigo and the eyes may show nystagmus (i.e., constantinvoluntary cyclical movement of the eyeball in any direction).

More recently, a technique has been developed that allows the atraumaticpreparation of implant sites by eliminating the use of a surgicalmallet. This procedure is based on the use of a ridge expansion systemthat includes a bur kit and instruments known as motor-driven boneexpanders, such as those marketed by Meisinger split control bonemanagement system (Neuss, Germany). First a pilot hole is drilled at theimplant site, then a series of progressively larger expander screw tapsare introduced into the bone by hand or with motor-driven rotation,which decreases surgical trauma (as compared with hammer taps) whileproviding superior control over the expansion site. See for example FIG.3. The thread pattern of the expander screw taps has been designed tocompact bone laterally as the instrument advances into the osseouscrest. This system allows expansion and preparation of implant sites inType II and III bone, as well as compaction of Type IV bone. TheMeisinger split control bone management system may be implemented with aso-called “expander bur” tool to prepare the initial pilot hole toreceive the first expander screw tap. In dentistry, the term “bur” isusually synonymous with “cutter.” The expander bur tool apparentlygrinds a taper on the inner wall of the pilot hole osteotomy that willreadily accept the tapered shape of the first expander screw tap.

Since they are operated with an electric hand piece, the expander screwtaps can be utilized in the anterior as well as posterior regionswithout impingement of the facial tissues or the positional limitationsimposed by traditional osteotomes (unlike a more traditionalmallet-driven osteotome which cannot easily reach for example the lowermandible posterior). Furthermore, the rotational control of theexpansion permits treatment of the mandibular atrophic ridge. The systemcan be utilized by itself or with osteotomes and surgical drills toassist in the placement of a variety of implant design.

US Publication No. 2006/0121415 to Anitua Aldecoa describes the use ofmotor-driven tools and methods for expanding a human bone for thepurpose of installing a dental implant. Similar to the progressiveillustration shown in FIG. 3, a starter drill is used to create a pilothole followed by the insertion of an expander screw tap type osteotomehaving a conical/cylindrical geometry with progressive cross-section. Asurgical motor is used to rotate the osteotome at relatively low speeds.Another example of this technique is described in U.S. Pat. No.7,241,144 to Nilo et al, issued Jul. 10, 2007. The entire disclosures ofUS Publication No. 2006/0121415 and U.S. Pat. No. 7,241,144 are herebyincorporated by reference.

In the prior art designs involving motor-driven bone expansion, therotary speed of the expander screw tap is locked in a fixed relationshipto the expansion rate of the osteotomy. This is because the expander tapthreads cut into the bone and advance the expander tap deeper into theinitial osteotomy with rotation. The “root” of the expander screw tapdoes the expanding work while vertical advance is controlled by pitch ofthreads and rotation speed. In other words, the thread pitch of theexpander screw tap combined with its taper angle is fixed and cannot bealtered by the surgeon. If a surgeon wishes to expand the bone moreslowly, the only recourse is to turn the expander more slowly.Conversely, if they wish to expand the bone more rapidly, the onlyoption is to turn the expander tool more quickly. Thus, the rate of boneexpansion is a direct and unalterable function of the rate at which thesurgeon turns the expander tool, and the surgeon is unable to vary otherparameters such as pressure and/or rotation rate to achieve an optimumexpansion rate.

The utilization of motor-driven bone expanders served in the past (FIG.3) as an innovative technique offering an atraumatic alternative to thetraditional mallet-driven osteotomes (FIG. 2). These instruments alsoprovide, at least arguably, a favorable increase in the control of thebone expansion, which facilitates implant-site preparation whileallowing universal intraoral use. Nevertheless, there are manyshortcomings of the present motor-driven bone expander screw taptechniques. These shortcomings include a relatively large number ofintermediate progressive expansions steps due to the surgeon's inabilityto disassociate the tool rotation rate from the bone expansion rate.Thus, a typical osteotomy kit may include 4-6 expander screw taps whichmake the kit cost relatively expensive. Another disadvantage is thateach expander screw tap takes time to install and perhaps an equalamount of time to remove (i.e., un-screw). Because of the relativelylarge number of progressive expansions steps needed, this translates toa long surgical procedure which increases patient discomfort andprocedure cost. Yet another disadvantage is that each rotary expansionstep introduces some degree of error into the osteotomy. The surgeon'shand controlling the advancing expander screw tap is typically locatedoutside the patient's mouth, which is laterally offset from therotational axis of the expander tap. Thus, even though a surgical motormay be used to drive the expander tap, there is a very real possibilitythat the surgeon will introduce the some tilt or wobble inadvertently asthe expander tap is advanced (or withdrawn) thus distorting the intendedshape of the osteotomy or even worse provoking a lateral fracture in thebone.

This inexorable linking of tool rotation rate to bone expansion rate inall prior art rotary expander systems limits surgical control over theimplant process, and in some cases may lead to unnecessary patientdiscomfort. There is therefore a need in the art for an improvedsurgical method for expanding an initial osteotomy to receive a dentalimplant, and tools therefor, that provide greater surgical control, areless costly, less likely to introduce error and that reduce patientdiscomfort.

SUMMARY OF THE INVENTION

This invention contemplates a surgical method for expanding an initialosteotomy to receive a dental implant. An osteotome is provided having atapered working end. The tapered working end of the osteotome isinserted into an initial osteotomy. The initial osteotomy has aninterior surface surrounded by bone. The initial osteotomy is enlargedby forcibly advancing the osteotome into the initial osteotomy. Theinserting and enlarging steps are repeated, as needed, withprogressively larger tapered osteotomes until an osteotomy ofpredetermined size is achieved. Finally, a fixture portion of a dentalimplant is installed into the expanded osteotomy. The invention isdistinguished by the working end of the tapered osteotome having one ormore longitudinally extending burnishing edges. The enlarging stepincludes simultaneously rotating and pushing the working end of thetapered osteotome into the osteotomy so that the one or more burnishingedges concentrate the pushing and rotational force through theburnishing edge in outward normal and tangential component forcesagainst the interior surface of the osteotomy to incrementally expandthe osteotomy with little to no removal of bone material.

Burnishing is the deformation of a surface due to stressed contact withanother object. Burnishing is commonly used in metalworking as a coldforming process, without actual removal of metal, where a tool is rubbedon the metal surface of the part with sufficient force to cause plasticflowing of the metal. The technique of burnishing is not commonlyapplied in the dental arts, and is heretofore not been applied insurgical procedures to expand an initial osteotomy for the purpose ofreceiving a dental implant.

According to another aspect of this invention, a burnishing osteotome isprovided comprising a longitudinally extending shank and a working end.The shank has a coupling at one end thereof, and the working end extendslongitudinally from the shank opposite the coupling. The working end hasa taper along its length. The working end includes a root shaft. Aplurality of flutes extend from the root shaft. Each the flute extendsradially outwardly to a crest. Due to the taper, the crest defines themajor diameter of the working end as a function of length. Alongitudinally extending burnishing edge is disposed along each crest.The burnishing edge is non-rotatably fixed relative to the root shaft,and is defined by a large negative rake angle.

This invention overcomes the disadvantages and shortcomings of prior artosteotome techniques offering an atraumatic alternative to thetraditional mallet-driven osteotomes without any disadvantages of rotaryexpander screw tap systems. The present surgical method and accompanyingsurgical tool for implementing the method provides a highlycontrollable, relatively fast and effective technique for expanding aninitial osteotomy to receive a dental implant. By forcibly rubbing theburnishing edges of the osteotome against the interior surfaces of theosteotomy, the bone material is effectively expanded and simultaneouslycompressed without creating excessive heat or trauma to the bonematerial. Because the concepts of this invention de-link rotation rateof the tool to the bone expansion rate, the surgeon is provided withsubstantially greater control which reduces the possibility for theintroduction of inadvertent lateral forces prevalent with prior artexpander screw tap devices. Surgical procedures according to the presentmethods can be carried out over less time, thereby resulting in lesstrauma and discomfort for the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome more readily appreciated when considered in connection with thefollowing detailed description and appended drawings, wherein:

FIG. 1 is a modified cross-sectional view through jawbone showing anexemplary dental implant in bone composed of a lower fixture portion andan upper restoration, the dental implant being flanked on either side bynatural teeth;

FIG. 2 is a simplified schematic view illustrating a progressivesurgical procedure according to the prior art wherein an initialosteotomy is progressively expanded to receive a dental implant using atraditional mallet-driven osteotome technique;

FIG. 3 is a view as in FIG. 2 but showing prior art expander screw taptechnique which has seeks to replace the mallet-driven osteotometechnique of FIG. 2;

FIG. 4 is a perspective view of an osteotome according to one embodimentof the present invention;

FIG. 5 is a side elevation view of the osteotome shown in FIG. 4;

FIG. 6 is a cross-sectional view through the working end of theosteotome as taken generally along lines 6-6 in FIG. 5;

FIG. 7 is a cross-sectional view through the working end of an osteotomeas taken generally along lines 6-6 in FIG. 5 but looking the otherdirection which, in use, is downwardly into an osteotomy, with radiallines emanating from the burnishing edges of the osteotome to indicatelaterally outward expansive forces applied through the burnishing edgesto the interior surface of an osteotomy;

FIG. 8 is an enlarged view of the area circumscribed at 8 in FIG. 7 anddepicting the interaction between the burnishing edge of the flute ofthe osteotome and the interior surface of the osteotomy, with radial andlongitudinal forces indicated by arrows;

FIG. 9 is a fragmentary perspective view showing the working end of anosteotome according to one embodiment of this invention having sixstraight flutes;

FIG. 10 is a fragmentary perspective view of an alternative osteotomeconfiguration according to this invention wherein the working end isconfigured with ten spiral flutes;

FIG. 11 is a front elevation view of an osteotome embodiment accordingto this invention including six straight flutes;

FIG. 12 is a front elevation view of a prior art osteotome of themallet-driven type shown for comparison purposes adjacent to theosteotome of FIG. 11;

FIG. 13 is a front elevation view of an alternative embodiment of anosteotome according to the subject invention including six helicallyspiraling flutes shown for comparison purposes adjacent the prior artosteotome of FIG. 12;

FIG. 14A is a simplified cross-sectional view through a bone preparedfor surgical expansion with a pilot drill having created an initialosteotomy site;

FIG. 14B is a view taken generally along lines 14B-14B in FIG. 14A;

FIG. 15A is a simplified surgical procedure showing a progression fromthat of FIG. 14A with a first osteotome having been inserted into theinitial osteotomy to expand the initial osteotomy into a first expandedosteotomy;

FIG. 15B is a view taken generally along lines 15B-15B of FIG. 15A;

FIG. 16A shows a further progression in the surgical procedure from thatof FIG. 15A in which a second osteotome is inserted into the osteotomyand operated in a manner so as to expand the osteotomy further;

FIG. 16B is a view as taken generally along lines 16B-16B in FIG. 16A;

FIGS. 17A and 18A show further progressions in the expansion processfrom that depicted in FIGS. 14A and 15A and 16A;

FIGS. 17B and 18B are views taken from lines 17B-17B and 18B-18B inFIGS. 17A and 18A, respectively;

FIG. 19A is a cross-sectional view of the region as in FIG. 18A showingthe installation of an implant into the fully enlarged preparedosteotomy;

FIG. 19B is a view as taken along lines 19B-19B in FIG. 19A;

FIG. 20 is a simplified cross-sectional view showing a surgicalprocedure referred to herein as “bounce” where an osteotome according tothe present invention is repeatedly pushed into the osteotomy andwithdrawn while the osteotome remains spinning in a repetitive manner soas to enlarge the osteotomy while enabling the surgeon to manage heatbuild-up and make adjustments on-the-fly; and

FIG. 21 is a simplified flow chart depicting the primary steps in thesubject method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the figures wherein like numerals indicate like orcorresponding parts throughout the several views, a burnishing osteotomeaccording to the present invention is generally shown at 22 in FIGS.4-11 and 13. The osteotome 22 comprises a longitudinally extending shank24. The shank 24 has a coupling 26 at one end thereof to attach to arotary input such as from a surgical motor having speed and torquecontrols. The osteotome 22 also includes a working end 28. The workingend 28 extends longitudinally from the shank 24 opposite the coupling26, and has a length of approximately 11-15 mm, although longer orshorter lengths may also be fashioned to suit the application. Asperhaps best shown in FIG. 5, the working end 28 has a taper along atleast a portion of its length. A leading distal tip 30 of the workingend 28 defines a minimal outer diameter, and an upper end 32 defines amaximum outer diameter of the tapered portion. The difference betweenthe minimal outer diameter (at 30) and the maximum outer diameter (at32) is preferably 1 mm, although larger or smaller differences can beachieved with larger or smaller taper angles.

Referring now to the cross-sectional views of FIGS. 6 and 7, the workingend 28 is shown including a root shaft 34, from which at least one, butmore preferably a plurality of flutes 36 extend. The plurality of flutes36 may comprise at least three flutes 36. Preferably, the plurality offlutes 36 are equally circumferentially spaced from one another so thatif there are four flutes 36 they are arranged 90° apart; six flutes 36would be arranged 60° apart; eight flutes 36 would be arranged 45°apart; ten flutes 36 would be arranged 36° apart; and so on.

Each flute 36 extends radially outwardly to a crest 38 which defines themajor diameter of the working end 28 as a function of length. That is,because the working end 28 is tapered, its diameter changes along itslength. Therefore the major diameter adjacent the distal tip 30 will besmaller than the major diameter adjacent the upper end 32. Thus, themajor diameter is a function of length measured as it were from thedistal tip 30. As perhaps best shown in FIG. 8, a longitudinallyextending burnishing edge 40 is disposed along the outermost portion ofthe crest 38. Thus, the burnishing edge 40 is that specific portion ofthe crest 38 which lies along the major diameter of the tapered workingend 28. In the embodiments illustrated in the drawing figures, theburnishing edge 40 in each instance is non-rotatably fixed relative tothe root shaft 34. This is due in large part to manufacturingconstraints for the relatively small osteotome sizes. However, ifmanufacturing techniques permitted, the burnishing edge 40 could beformed by a roller element in order to reduce friction and better manageheat build-up.

Returning again to FIG. 8, the crest 38 is shown as establishing a largenegative rake angle leading up to the burnishing edge 40. A rake is anangle of slope measured from the leading face of the tool (the crest 38in this case) to an imaginary line extending perpendicular to thesurface of the worked object (e.g., inner bone surface of theosteotomy). Rake angle is a parameter used in various cutting andmachining processes, describing the angle of the cutting face relativeto the work. There are three types of rake angles used in metal working:positive, negative, and zero. However, in the preferred embodiment ofthis present application of a burnishing technique, a negative rakeangle is employed, and more preferably a large negative rake angle.While the actual angle of the negative rake is adaptable to suit theparticular specifications, including the relative roundness or sharpnessof the burnishing edge 40, negative rake angles greater than about 45°,and even more preferably greater than 60°, have been found to producesatisfactory results. The large negative rake angle of the presentosteotome 22 applies outward pressure at the burnishing edge 40 tocreate a compression wave ahead of the point of contact, loosely akin tospreading butter on toast. Downward pressure applied by the surgeon isneeded to keep the burnishing edge 40 in contact with the bone surfaceof the osteotomy being expanded, that is, to keep it pushing on thecompression wave. This is aided by the taper effect of the osteotomy andtool 22 to create lateral pressure (i.e., in the intended direction ofexpansion). The harder the surgeon pushes down, the more pressure isexerted laterally. This gives the surgeon complete control of theexpansion rate irrespective to a large degree on the rotation speed ofthe osteotome 22. Thus, the burnishing effect's intensity depends on theamount of force exerted on the osteotome 22. The more force exerted, thequicker expansion will occur

As shown in the enlarged and somewhat exaggerated for clarity FIG. 8, asthe burnishing edge 40 drags across the bone, the force on theburnishing edge 40 can be decomposed into two component forces: onenormal to the bone's surface, pressing it outwardly, and the othertangential, dragging it along the inner surface of the osteotomy. As thetangential component is increased, the burnishing edge 40 will start toslide along the bone. At the same time, the normal force will deform thesofter bone material. If the normal force is low, the burnishing edge 40will rub against the bone but not permanently alter its surface. Therubbing action will create friction and heat, but this can be controlledby the surgeon by altering, on-the-fly, the rotation speed and/orpressure and/or irrigation flow. As will be described subsequently inconnection with FIG. 20, because the working end 28 of the osteotome 22is tapered, the surgeon may at any instant during the surgical procedurelift the burnishing edges 40 away from contact with the surface of thebone to allow air cooling or irrigation. This can be done in acontrolled “bouncing” fashion where pressure is applied in short burstswith the surgeon continuously monitoring progress and making finecorrections and adjustments. Conversely, as the normal force increases,eventually the stresses in the bone's surface exceed its yield strength.When this happens, the burnishing edge 40 will plow through the surfaceand create a trough behind it. The plowing action of the burnishing edge40 thus progressively enlarges the osteotomy. While the elasticproperties of bone are well-known, if the load imposed exceeds thebone's ability to deform elastically, it will deform further and changeshape permanently by plastic deformation. The permanent change in shapeis believed to be associated with micro-cracks that allow energyrelease, a compromise that is a natural defense against completefracture. If these micro-cracks are small, the bone remains in one piecewhile the osteotomy expands.

Said another way, expansion of the osteotomy occurs when the burnishingedge 40 is rotated against the bone surface of the osteotomy anddownward pressure is applied by the surgeon. This has the effect ofcausing, at the same time, rotation and translation of the burnishingedge 40, but in a manner that does not positively link rotation andtranslation as in prior art expander screw tap devices. The osteotomy,therefore, is formed into the final size ready to receive the fixtureportion of a dental implant by a series of small incremental plasticdeformations created by sweeps of successive burnishing edges 40 pressedhard against the interior surface of the osteotomy. Each such plasticdeformation is followed by a short interval of rest before the arrivalof the next successive burnishing edge 40.

The burnishing edge 40 is shown in as comprising a chisel-like shapeheld at the previously described large negative rake angle. However,those of skill will appreciate that the burnishing edge 40 could beformed by other crest 38 profile shapes, such as rounded or lobeddesigns, provided the manufacturing techniques required to make such analternative profile were found to be cost-justified in comparison withthat of the preferred profile as shown in FIGS. 7 and 8.

Turning now to FIGS. 9-13, the illustrations depict various embodimentin which the flutes 36, and thus by extension the burnishing edges 40,may be formed either with no twist, i.e., straight as in FIGS. 9 and 11,or with a spiral twist along the length of the working end 28 as inFIGS. 10 and 13. A prior art osteotome of the mallet-driven type isshown for side-by-side comparison purposes in FIG. 12.

Turning now to FIGS. 14A-20, surgical methods are depicted for expandingan initial osteotomy 42 to receive a dental implant 44. Typically as afirst step an initial osteotomy site is prepared by exposing bone 46,and then drilling a pilot hole into the bone 46 with a pilot drill 48.This is shown in FIG. 14A, and may be accomplished with a typical priorart surgical pilot drill 48 turned in a standard clock wise direction.The pilot hole in this instance comprises the initial osteotomy 42. Insome cases, the surgeon may decide it is beneficial to saw a groove 50along the bone ridge as seen in FIG. 14B. The sawed groove 50 typicallyintersects the pilot hole 42 along the ridge of the bone 46. The surgeonmay decide to first drill the pilot hole and then saw the groove 50, orvice versa.

A first osteotome 22 according to the present invention is operativelyconnected to a surgical motor (not shown) though its coupling 26feature. Then the working end 28 of the first osteotome 22 is insertedinto an initial osteotomy 42. The interior surface of the initialosteotomy 42 is surrounded by bone 46. If the diameter of the pilotdrill 48 is, for example 1.5 mm, then preferably the major diameter ofthe working end 28 of the first osteotome 22 adjacent the leading distaltip 30 is also 1.5 mm so that it follows easily the pilot hole. Becauseof the widening taper, the major diameter of the working end 28 adjacentupper end 32 is larger than the initial osteotomy. This may be, forexample, 2.5 mm. At these exemplary dimensions, a first osteotome 22having six equally spaced flutes 36/burnishing edges 40 of straight orhelical twist has been found to provide satisfactory results. More orfewer flutes 36/burnishing edges 40 are certainly possible.

The initial osteotomy 42 is enlarged in a next step of the procedure byforcibly advancing the working end 28 of the first osteotome 22 into theinitial osteotomy 42, which is depicted in FIG. 15A. This forcibleadvancing includes simultaneously rotating and pushing the working end28 of the first tapered osteotome 22 into the osteotomy 42 so that itsone or more burnishing edges 40 concentrate the pushing and rotationalforce in outward normal and tangential component forces (FIG. 8) againstthe interior surface of the osteotomy 42. FIG. 15A illustrates acounter-clockwise rotation of the osteotome 22, but that direction ismerely preferred and can be reversed with suitable alterations made tothe shape of the osteotome 22. Although the surgeon may vary therotational speed of the osteotome 22 according to the dictates of thesituation in their judgment, experimental results indicate that rotationspeeds greater than about 200 RPM and torque settings greater than about15 Ncm provide satisfactory results. More preferably rotation speedsgreater than about 600 RPM and torque settings greater than about 20 Ncmprovide satisfactory results. And still more preferably, rotation speedsin the range of 800-900 RPM and torque settings of about 35 Ncm providesatisfactory results.

As perhaps best shown in FIG. 20, the enlarging step may include thecontrolled practice of bouncing the burnishing edges 40 into and out ofcontact with the interior surface of the osteotomy 42 while continuouslyrotating the osteotome 22. This practice is unachievable using prior artosteotome tools and techniques (as shown in FIGS. 2, 3 and 12). However,because the subject osteotome 22 has a tapered working end 22 and onlythe burnishing edges 40 are ever in contact with the interior surface ofthe osteotomy 42, the surgeon may at any time lift the working end 28out of contact to evaluate progress, manage heat, irrigate, adjustapproach, or make other corrections. In fact, the surgeon may practice avery controlled technique whereby the burnishing edges 40 are repeatedand successively pushed into and pulled out of the osteotomy 42 in asort of bouncing maneuver. Although this bouncing technique is notrequired for proper execution of the method, the novel tool shape andother features of this invention enable the bouncing technique if andwhenever the surgeon warrants.

It should also be mentioned that if the surgeon warrants, the osteotome22 may be rotated in the opposite direction (e.g., clockwise in theseexamples) and utilize the osteotome 22 to enlarge the osteotomy 42 bycutting or excavating bone material from the osteotomy 42 rather thanvia compression and plastic deformation.

When the full length (approximately 11-15 mm) of the working end 28 hasbeen advanced into the osteotomy, the resultant effect is an incrementalexpansion of the osteotomy 42 to the dimensions of the working end 28with little to no removal of bone material 46. The first osteotome 22 isthen removed from the osteotomy 42 to reveal a first enlarged osteotomy42. The first enlarged osteotomy 42 is fully prepared and ready toreceive the implant 44 if, in this example with the given dimensions,the fixture portion is sized at about a 3.0 mm diameter.

If the fixture portion of the implant 44 is larger than 3.0 mm(continuing with this example for purposes of illustration), then thefirst enlarged osteotomy 42 must be enlarged still further. This isaccomplished by repeating the inserting and enlarging steps withprogressively larger tapered osteotomes 22, as needed, until anosteotomy 42 of predetermined size is achieved. More specifically, asshown in FIG. 16A, a second osteotome 22 having a tapered working end 28that is larger in diameter than the first osteotome 22, is operativelyconnected to the surgical motor (not shown). The tapered working end 28of the second osteotome 22 is inserted into the first enlarged osteotomy42. Using the previously described exemplary dimensions, the majordiameter of the working end 28 of the second osteotome 22 adjacent theleading distal tip 30 is 2.5 mm so that it follows easily the firstenlarged osteotomy 42. Because of the widening taper, the major diameterof the working end 28 adjacent upper end 32 is, for example, 3.5 mm. Atthese exemplary dimensions, the second osteotome 22 having eight equallyspaced flutes 36/burnishing edges 40 of straight or helical twist hasbeen found to provide satisfactory results. More or fewer flutes36/burnishing edges 40 are certainly possible.

The surgeon proceeds to further enlarge the first enlarged osteotomy 42by forcibly advancing the second osteotome 22 into the first enlargedosteotomy 42 to create a second enlarged osteotomy 42. As before, theadvancing step is comprised of simultaneously rotating and pushing theworking end 28 of the second tapered osteotome 22 into the osteotomy 42so that its one or more burnishing edges 40 concentrate the pushing androtational force in outward normal and tangential component forces (FIG.8) against the interior surface of the osteotomy 42. When the fulllength (approximately 11-15 mm) of the working end 28 has been advancedinto the osteotomy 42, the second osteotome 22 is then removed from theosteotomy 42 to reveal a second enlarged osteotomy 42. The secondenlarged osteotomy 42 is fully prepared and ready to receive the implant44 if, in this example with the given dimensions, the fixture portion issized at about a 4.0 mm diameter.

If the fixture portion of the implant 44 is larger than 4.0 mm(continuing with this example for purposes of illustration), then thesecond enlarged osteotomy 42 must be enlarged still further. This isaccomplished by repeating the inserting and enlarging steps with aprogressively larger tapered osteotome 22. FIG. 17A illustrates thisscenario where a third osteotome 22 is operatively connected to thesurgical motor. Its tapered working end 28 is inserted into the secondenlarged osteotomy 42. Using the previously described exemplarydimensions, the major diameter of the third osteotome 22 adjacent itsleading distal tip 30 is 3.5 mm, and adjacent its upper end 32 may, forexample, be 4.5 mm. At these exemplary dimensions, the third osteotome22 may have ten equally spaced flutes 36/burnishing edges 40 of straightor helical twist, although more or fewer flutes 36/burnishing edges 40are certainly possible.

The surgeon proceeds to further enlarge the second enlarged osteotomy 42by simultaneously rotating and pushing the working end 28 of the thirdtapered osteotome 22 into the osteotomy 42 so that its one or moreburnishing edges 40 concentrate the pushing and rotational force inoutward normal and tangential component forces (FIG. 8) against theinterior surface of the osteotomy 42. When the full length(approximately 11-15 mm) of the working end 28 has been advanced intothe osteotomy 42, the third osteotome 22 is then removed from theosteotomy 42 to reveal a third enlarged osteotomy 42. The third enlargedosteotomy 42 is fully prepared and ready to receive the implant 44 if,in this example with the given dimensions, the fixture portion is sizedat about a 5.0 mm diameter.

If the fixture portion of the implant 44 is larger than 5.0 mm(continuing with this example for purposes of illustration), then thethird enlarged osteotomy 42 must be enlarged still further. This isaccomplished by repeating the inserting and enlarging steps with aprogressively larger tapered osteotome 22. FIG. 18A illustrates use of afourth osteotome 22 having (for example) a major diameter adjacent itsleading distal tip 30 of 4.5 mm, and adjacent its upper end 32 of 5.5mm. At these exemplary dimensions, the fourth osteotome 22 may havetwelve equally spaced flutes 36/burnishing edges 40 of straight orhelical twist, although more or fewer flutes 36/burnishing edges 40 arecertainly possible.

The surgeon proceeds to further enlarge the third enlarged osteotomy 42by simultaneously rotating and pushing the working end 28 of the fourthtapered osteotome 22 into the osteotomy 42. As before, the one or moreburnishing edges 40 concentrate the pushing and rotational forcesagainst the interior surface of the osteotomy 42. When the full length(approximately 11-15 mm) of the working end 28 has been advanced intothe osteotomy 42, the fourth osteotome 22 is then removed from theosteotomy 42 to reveal a fourth enlarged osteotomy 42. The fourthenlarged osteotomy 42 is fully prepared and ready to receive the implant44 if, in this example with the given dimensions, the fixture portion issized at about a 6.0 mm diameter.

To complete the example, FIG. 19A shows the 6.0 mm diameter fixtureportion of an implant 44 installed into the fourth enlarged osteotomy42. The step of installing a fixture portion of an implant 44 includesdirectly engaging an exterior anchoring thread form 52 of the fixtureportion into the expanded osteotomy formed by the burnishing edge 40.

The surgical method of this invention, and in particular the diameter towhich the osteotomy 42 can be ultimately expanded, is of course limitedby the physical properties of the bone 46 and other factors. In otherwords, the steps of expanding as described herein are directly relatedto the final desired fixture 44 diameter but also related to the abilityof the bone 46 to plastically deform (via the above-describedmicro-cracks) without fracturing. For example, in some conditions it isnot possible for even a skilled surgeon to take a 3 mm width of bone 46and use the procedures of this invention to expand an osteotomy 42 allthe way to 5.5 mm without fracturing the bone 46. However, it may bepossible to expand the osteotomy 42 to a slightly smaller 4.5 mm so thatit will receive a 5 mm diameter implant 44. Thus, it should beunderstood that bone's ability to plastically deform without fracturingdictates how much expansion can be achieve, and also dictates at whichstep the surgeon must to stop the expansion process to avoid fracturingthe bone 46.

The surgical method of this invention enables an expansion of an initialosteotomy 42 to receive a dental implant 44 that is significantly lesstraumatic than other prior art osteotome techniques, that is faster thanother prior art osteotome techniques, that is able to rear previouslydifficult to reach areas (e.g., the lower mandible posterior), thatrequires fewer progressive steps (and tools) to achieve a final enlargedosteotomy than other prior art osteotome techniques, and that issignificantly better at managing heat build-up than other prior artosteotome techniques. Heat management is enhanced through irrigationinto the osteotomy (difficult with prior art techniques) and also bymaintaining a separation space between the root shaft 34 and the boneinterior surface of the osteotomy 42. This separation space means lessfriction and also the opportunity for some degree of convective cooling.

The foregoing invention has been described in accordance with therelevant legal standards, thus the description is exemplary rather thanlimiting in nature. Variations and modifications to the disclosedembodiment may become apparent to those skilled in the art and fallwithin the scope of the invention.

What is claimed is:
 1. A surgical method for installing a dental implantin bone, said method comprising the steps of: preparing an initialtreatment site, said preparing step including drilling a pilot hole intothe bone, the pilot hole comprising an initial osteotomy; providing afirst osteotome having a tapered working end; operatively connecting thefirst osteotome to a surgical motor; inserting the tapered working endof the first osteotome into the initial osteotomy; enlarging the initialosteotomy by forcibly advancing the first osteotome into the initialosteotomy to create a first enlarged osteotomy; removing the firstosteotome from the first enlarged osteotomy; providing a secondosteotome having a tapered working end, the tapered working end of thesecond osteotome being larger in diameter than the tapered working endof the first osteotome; operatively connecting the second osteotome to asurgical motor; inserting the tapered working end of the secondosteotome into the first enlarged osteotomy; further enlarging the firstenlarged osteotomy by forcibly advancing the second osteotome into thefirst enlarged osteotomy to create a second enlarged osteotomy; removingthe second osteotome from the second enlarged osteotomy; the workingends of the first and second tapered osteotomes each having a pluralityof longitudinally extending burnishing edges; said enlarging and furtherenlarging steps including continuously rotating the working ends of therespective tapered first and second osteotomes while concurrentlypushing the working ends of the respective tapered first and secondosteotomes into the osteotomy so that the respective burnishing edgeslap against the interior surface of the respective initial and firstosteotomies without cutting into the surrounding bone; and irrigatingthe initial osteotomy and the first enlarged osteotomy concurrently withsaid respective enlarging and further enlarging steps.
 2. The surgicalmethod of claim 1, wherein the first osteotome has a predeterminednumber of burnishing edges, and wherein the second osteotome has agreater number of burnishing edges than the predetermined number ofburning edges of the first osteotome.
 3. The surgical method of claim 1,wherein at least one of said enlarging and further enlarging stepsincludes axially pumping the working end of the respective first andsecond tapered osteotomes so that the respective burnishing edgesalternately contact and separate from the interior surface of theosteotomy.
 4. A surgical method for enlarging an osteotomy to receive adental implant using continuous high-speed rotation of a dental bur,said method comprising the steps of: providing a dental bur having atapered working end, the working end having a plurality oflongitudinally extending blades; positioning the tapered working end ofthe dental bur so as to enter an osteotomy to be enlarged, the osteotomyhaving a generally cylindrical or tapered interior surface of bone;rotating the working end of the dental bur at high speed; pushing thetapered working end into the osteotomy concurrently with said rotatingstep so that expansion of the osteotomy occurs in a frustoconicallyexpanding manner as the blades sweep against the interior surface of theosteotomy in ever-deepening movements; and irrigating the osteotomyconcurrently with said pushing step.
 5. The surgical method of claim 4,wherein the working end of the dental bur includes a plurality of flutesextending from a root shaft, and wherein said pushing step includesmaintaining a separation space between the root shaft and the interiorsurface of the osteotomy.
 6. The surgical method of claim 5 wherein theplurality of flutes correspond in number to the plurality of blades, andsaid pushing step further includes manually applying variable axialpressure.
 7. The surgical method of claim 5, wherein the plurality ofblades are each defined by a negative rake angle.
 8. The surgical methodof claim 4, wherein the plurality of blades each have a spiral twistalong the length of the working end.
 9. The surgical method of claim 4,wherein the plurality of blades each have a generally straightconfiguration along the length of the working end.
 10. The surgicalmethod of claim 4, wherein said rotating step includes rotating theworking end of the dental bur at speeds greater than 200 RPM.
 11. Thesurgical method of claim 4, wherein said rotating step includes applyinga torque to the working end of the dental bur greater than 15 Ncm. 12.The surgical method of claim 4, wherein said pushing step includesaxially reciprocating the plurality of blades into and out of contactwith the interior surface of the osteotomy with a pumping motion. 13.The surgical method of claim 4, further including installing a dentalimplant into the expanded osteotomy, wherein said installing stepincludes directly engaging an exterior anchoring thread form of thedental implant into the expanded osteotomy formed by the plurality ofblades.
 14. The surgical method of claim 4, further including the stepof preparing an initial osteotomy site by drilling a pilot hole into thebone, the pilot hole comprising the initial osteotomy.